Time measuring system



lume 24, E947.

O. R. MILLER TIME MEASURING SYSTEM Filed Nov. 5. 1942 6 Sheets-Sheet 1 ATTORNEY June 24, 1947. o. R. MILLER TIME MEASURING SYSTEM Filed Nov. 5, 1942 6 Sheets-Sheet 2 l la.

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u' kl l mum /NVENTOR O. R. MILLER ATTORNEY Patented June 24, 1947 UNTED STATES PATENT OFFICE TIME MEASURING SYSTEM ohmer n. Miller, Morristown; N. J.. assigner to Beil Telephone Laboratories, Incorporated, Net.l York, N. Y., acorporation of New York Application November 5, 1942, Serial No. 464,667

' 1 Claim.

This invention relates to measuring systems and particularly to means for the accurate measurement of small intervals of time.

The object of the invention is to provide means for the extremely' accuratel measurement of a small time interval, particularly where such an interval is to be marked ofi for use as distinguished from the determination of a time interval after the event. It has heretofore been general practice to measure a time interval by computation of the number of cycles of a high frequency current which have occurred during the said time interval but this is an operation which could only be carried out at leisure after the event. In accordance with the present -invention the determination is made during the event and the reaching of a particular and predetermined number of such cycles is translated into a signal which serves to mark the end of a desired interval. Any

.desired degree of accuracy may be attained by .consists of a pair of electronic tubes having an incoming'and an outgoing circuit for. transmitting over said outgoing circuit one lpulse for every two pulses transmitted to said tubes over said incoming circuit. Given a plurality of sets of these tubes arranged in cascade, any number may be counted by a binary geometric progression system. By way of example, with fourteen sets of these tubes the number 16383 in the common decimal system may be counted as the number 11,111,111,111,111. 'I'he latter number, however, is awkward to handle and hence one aspect of the present invention is to provide an arrangement of counting tubes which will respond to numbers based on the decimal system.

In accordance with this object a device is provided having an incoming and an outgoing, circuit for transmitting over said outgoing circuit one pulse for every ten pulses transmitted to said device over said incoming circuit. With a plurality of such devices in cascade any number oi incoming pulses may be counted.

Further in accordance with the present invention means is provided to preset such a device so that it will give a response upon the reaching of va predetermined count. Thus an operation may be carried out by starting such an operation by a pulse and stopping the operation by a succeeding pulse. These two pulses may be accurately separated in time by having the starting pulse also serve to set a counting device into operation, which said counting device will then generate and transmit the stopping pulse when a predetermined number of pulses from a precisely regulated source of pulses has been counted.

A feature ot the invention is a time measuring device comprising a source of pulses, an electronic counter which will transmit one pulse for every ten pulses received.

Another feature of the invention is a pulse counter made up of a plurality of pairs of binary pulse counters responsive to incoming pulses to rearrange the internal conditions of such a device in accordance with a permutation code in a complete cycle of ten diiierent combinations and a means responsive to the rearrangement of said internal conditions into a particular one of said combinations for generating and transmitting a single outgoing pulse.

In another application, Serial No. 464,668 filed November 5, 1942, in the name of the same applicant, a submarine locating system is disclosed employing substantially the same arrangement as that disclosed herein. In another application, Serial No. 464,666 liled November 5, 1942, in the name of the same applicant, now Patent No. 2,407,320, a number` counter based on a similar disclosure is describedand claimed. l

The drawings consist'of six sheets having nine iigures, as follows:

Fig. 1 is a schematic diagram showing how the lm llllli-l-Wn various circuit elements are arranged to carry out the present invention;

Fig. 2 is a timing diagram showing the time relations between the various operations;

Fig. 3 is a circuit diagram showing details of the gate and recycle circuits; Y

Fig, 4 is a diagram partly schematic showing in full circuit diagram one impulse counter and indicating three others, it being intended to describe by way of example a four digit system;

Fig. 5 is a diagram also partly schematic showing in full circuit diagram one decade control, indicating three others, the circuit of what is termed the integrator and the gate and indicated counter for controlling the recycle circuit;

Fig. 6 is a diagram partly schematic showing in full circuit diagram the signal start circuit and te sweep start circuit and indicating the locating signal transmitting and receiving circuit, and the oscilloscope;

Fig. 7 is a schematic diagram indicating the thousands, hundreds, tens and umts counters by rectangles with fragmentary circuit diagrams in the hundreds and units counters to explain special points in connection with the invention;

Fig. 8 is a chart to show the sequence of operation of the counting tubes; and

Fig. 9 is a diagram showing how Figs. 3, 4, 5 and 6 may be placed to provide a complete circuit diagram.

'Ihis invention may be understood by the following description of the schematic diagram of Fig. 1. The invention is shown as a means cooperating with a submarine detecting device the details of which are not here disclosed. Such a device consists generally of means to send out a signal and to receive a return signal. If there is a foreign objectin the water the outgoing signal will be reflected back as an echo and the time taken between the transmission of the signal and the reception of the echo is a direct measure of the distance between the test point and the i'oreign object. Due to the fact that the return Signal or echo is greatly attenuated it is not of the same order as the outgoing signal and therefore cannot be used for direct action. Ordinarily when a time interval is to be measured impulses marking the beginning and the end of the interval are used to start and stop pulses to operate a gate circuit which thereupon allows a :dow of precisely timed pulses to a counting device so that the number counted will be in direct relation to the measured time interval. However, this return signal or echo is too feeble to act as a stop signal, and if amplied suiilciently for that purpose would produce unreliable results since other foreign pulses unavoidabiy received by the receiving apparatus would also be amplified and might give rise to false operation of the gate circuit. Experience has proved, however, that if the receiving device has been connected to operate an oscilloscope the return signal or echo may be deiinitely recognized.

In the jargon of the operators of these devices the signal may be seen in the grass which expressionu rather aptly describes the results attained with an oscilloscope. The noise, static or other source of pulses picked up appears as a buzz, rather dense and often of greater amplitilde than the signal being observed. 'I'he signal, however, is of a characteristic shape and is suiliciently distinct to be deilnitely recognized,

Iherefore a timed impulse generator is employed, which generator may be adjusted to transmit a pulse at the conclusion of any time interval desired. Now if the return signal or echo is viewed on an oscilloscope in comparison with such a timed pulse and the timed impulse generator is adjusted until the comparison shows equal times then the last setting of such adjustment means, which may aptly be termed a decade. will be a reading of the time interval which it is desired to measure and this interval will be a measure of the distance between the test point and the foreign object.

By way of example, let it be assumed that a measurement is made and the reading oi.' the decade comes out as 1882. It the oscillator used is a source of 800 cycle current. this would indicate that a time interval of 2.3275 seconds had been measured. It is known that the signal used travels at the rate of 1,600 yards per second. Therefore, the signal has travelled 3,724 yards, but since this is from the test point to the object and back, the object must behalf that distance or 1,862 yards away. 'I'hus by choosing an oscillator which has a rate corresponding to the rate of travel of the signal through water a direct reading may be made.

Using an 800 cycle oscillator and a four digit decade any time interval from 0 to 12.5 seconds may .be measured corresponding to 0 to 10,000 yards which amply provides' for a range up to 5,000 yards which is taken as the usual limit for these measurements.

In operating this device the approximate distance may be judged by the usual methods depending on the skill and experience of the operator or the entire range may be explored quickly by sequentially setting the thousands dial on its ten different positions. While other methods might be used, this is found by practical experience to be very satisfactory. 'I'he decade, indicated in Fig. 1 by the squares I, 2, 3 and I, is then set at such approximate reading. Thereafter a starting key incorporated in the gate circuit li is depressed for an instant to place the circuit into operation. 'I'his opens the gate 5 and allows current from the precision oscillator 6 to flow to the timed impulse generator comprising the counters 1, 8, 9 and I0. At the same instant a pulse is transmitted to the start circuit II to cause the submarine detecting device I2 to transmit its signal.

At the end of the interval measured by the timed impulse generator an impulse is sent to the sweep start circuit I3 which thereupon starts the sweep of the oscilloscope Il. If the adjustment is perfect, then at the instant that the sweep reaches the vertical center line of the oscilloscope I4, the return signal from the submarine detecting signal device I2 will be transmitted to the oscilloscope where it appears as a recognizable signal. The setting of the decade will then indicate the distance of the foreign object from the test point. v

The method of adjustment of the oscilloscope is as follows. It has been shown that by the use of a proper frequency for the source of oscillations that the setting of the decade adjusting means of the timed impulse generator may be made to give a direct reading in the number of yards distance between the test point and the foreign object. Now let us say that it will be oonsidered sufficiently accurate if the return signal is viewed in the oscilloscope within a range of one thousand yards. That is, experience has shown that an operator may judge by ear alone the distance to be measured within a thousand yards so that if the ilrst adjustment of the decade is made to correspond to the judged distance then the return signal will probably be seen on the oscillcope, since the sweep start circuit will be set to ve hundred yards before to ve hundred yards beyond the setting of the decade. Having then brought the signal to be observed within the range or the oscilloscope the decade may be adjusted until the observed signal occurs at the exact center line whereupon the reading of the decade will be a direct measure of the distance sought to be established,

For duiclr and rough operation the oscilloscope may be set to have the sweep travel over a great distance. By this means little or no time is lost in bringing the signal within the range of the oscilloscope but this is at the expense of accuracy in the distance measured. Ii extreme accuracy is desired then the oscilloscope may be adjusted to have the sweep travel over a short range, say one hundred yards.

Taking the one thousand yards then, by way oi example, the sweep must be Vmade to travel a time corresponding to five hundred yards before the center line is reached. This means that the last nve hundred yards is viewed in the oscilloscope or in other words that the sweep is started in operation five hundred yards before the return signal is detected. Now if the sweep is started in the exact time indicated by the decade the exact distance when the device is properly adjusted so that the return signal occurs at the zero or center line will be the reading of the decade plus ve hundred. Since such calculations must signal start circuit is taken from impulse counter 8 which counts the hundreds digits. When this be avoided, means may be provided to delay the transmission of the locating signal. Thus as means for making the reading of the decade correspond truly to the distance measured the pulse passed from the timed impulse generator to the start circuit i i may be delayed after the gate circuit e has been opened until ve hundred pulses have been counted. Thus if the start circuit ii operates on the iive hundredth pulse and the return signal is not seen in the oscilloscope until ve hundred pulses, corresponding to ve hundred yards, beyond the timed pulse from the timed pulse generator, then the reading of the decade will be in true correspondence with the distance to be measured. As an alternative method, means are provided to preset the counter so that the count is started from five hundred. Thus the reading of the decade will represent the true distance being measured. It follows that if the decade reads 1,862 and the signal is observed at what would be l,862+500 or 2,362 thenthe true reading would be 2,362--500 or 1,862.

The timed impulse generator Working through a circuit which may be termed an integrator and designated by the numeral i in Fig. l sends the impulse to the sweep start circuit le and also to a gate circuit it I,whereby a counter il is set into operation. Upon the completion of a count by this device of sucient duration the recycle circuit will be operated for the purpose of resetting all the circuits involved and then restarting them again. lf it is found desirable the time counted by the counter il may be adjusted to give the operator suiicient time to rcadjust the decade.

Two methods of shifting the two time intervals being compared will be explained. The rst method consists in delaying the sending of the signal to the start circuit il until a time equal to one haii the sweep time of the oscilloscope hasy been counted. By 'way of example this has beenl set at a count of five hundred. Therefore, the connection between the impulse counter and the counter responds to its fifth pulse, a signal will be transmitted over the lead i9 or Fig. l. Therefore, the locating signal is started late by a count of five hundred so that atthe end of the measured time interval as determined by the decade the locating signal still has a period of time represented by a count of ve hundred to travel before it appears on the oscilloscope. In this case all of lthe various pieces of apparatus which are controlled over the reset lead 2o will be returned to their zero positions.

The operation may then be visualized with the aid or the time diagram of Fig. 2. This shows a single cycle of operation. The time set by the decade is counted over a period from the time designated start of count. One half the sweep time thereafter the time of the travel of the locating signal is started. At the end of the time set by the decade the sweep is started so that the end of the travel time of the location signal should coincide with the middle oi the sweep time. Therefore if the decade has been properly set the return signal will be seen at the center line of the oscilloscope.

.et the end or" the time set by the decade the counter il will start into operation and at some convenient time thereafter as determined by experience and the time required by the operator to properly adjust the decade the recycle operation will The gate E is immediately closed and shortly thereafter a. reset puise is transmitted which will` return all the apparatus to normal. Shortly after the reset pulse and at a time interval which is sumcient for the apparatus to have denitely regained their normal positions the gate 5 is opened whereupon the full cycle of operations is repeated.

Another method of shifting the relation 'between the two time intervals which are being compared is to preset the impulse counter so that the count instead oi starting at one will start say at five hundred and one. in this Way if the decade is set at 1,862 then only 1,362 pulses will be counted and since the time of the location sig`' nal begins with the beginning of such count it effectively starts ve hundred pulses after the time measuring operation controlled by the decade.

in this case the reset lead to impulse counter 8 instead of returning this counter to zero will return it to five. As will be seen hereinafter a key may be provided which will transfer the reset lead from one point to another so that with the key in one position the counter will be returned to zero and in another position the counter will be set at five.

Also in this case the lead I9 of Fig. l will be taken from impulse counter ill instead of impulse counter 8 since the signal start circuit is to be enabled as soon as the gate d is opened.

The complete operation of this device will be understood from the following description. Assuming that all the apparatus is in normal condition the device may be put into operation by the operation of a key or switch 2l. This connects a precision oscillator 2i through a condenser 23 to tube 2d in the gate circuit shown in the upper part vof Fig. 3. Throughout the drawings wherever ionic tubes are shown the laments for heating such tubes are indicated but the battery supply is not shown since the manner of making such connections is well known and the addition of such circuits would unnecessarily complicate the 'negative pulse.

drawings. The alternating current supplied bythe precision oscillator is in the form of a sinusoidal wave whose frequency is very accurately regulated. 'I'his wave is biased through a connection through resistance to apotentiometer point formed by the junction of resistances 26 and 21 between negative battery and ground. The plate of tube 24 being connected through condenser 28 and resistance 29 to ground and to the grid of inverted tube 30, the output of tube 24` will appear on the grid of tube 30 as a train of accurately timed negative pulses. Tube 30 inverts these so that conductor 3| supplies a. train of accurately timed positive pulses to the counting devices.

As shown in Fig. 4 there are four counting devices shown'in cascade, one being shown in full and the other three being shown schematically. If'that. one shown in detail is arranged as the thousands counter then those indicated by the rectangles 32, 33 and 34 will be the hundreds. tens and units counters respectively. Each counter has an in and an out" conductor and the pulse supply lead 3| will be connected to the in conductor of the units counter 34, the out conductor of the units counter 34 will be connected to the in conductor of the tens counter 33, the out conductor of the tens counter 33 will be connected to the in" conductor of the hundreds counter 32, and the out conductor of the hundreds counter 32 will be connected to the in conductor of the thousands counter 35. For purposes of explanation it will therefore be assumed that a train of positive pulses will appear on the in conductor of the thousands counter 35 and after passing through condensers 36 and 31 will appear on the control grids of tubes 39 and 4|), respectively.

Throughout this device a large number of counting tubes are employed. By way of example a single pair will be described in detail so that the operation of the device as a Whole may be readily understood. The principle of operation is fundamentally the same as that of the` well-known Eccles and Jordan circuit, disclosed in British Patent 148,582. In the present circuit the tubes are, however, pentodes with the anode of each connected to the screen grid of the other. When a negative impulse is applied to the suppressor grid of both, then both are rendered nonconducting. When the said negative impulse has ceased, the combination of the two tubes is left in an extremely unstable state so that the slightest influence will determine which of the two is to become conducting to the exclusion of the other. This extremely slight iniluence is supplied by a condenser 49 connected between the cathodes of tubes 43 and 44 whose operation will be described by Way of example. While tube 43 is active and tube 44 is inactive condenser 49 is charged in one direction and While tube 44 is active and tube 43 is inactive condenser 49 is charged in the opposite direction. When the negative impulse is applied to the two suppressor girds, condenser 49 becomes discharged but there is left a slight residual charge, the magnitude of which depends on the eiective length of the said At the termination of this negative pulse the said slight residual charge on condenser 49 is sufficient to determine which of the two tubes will then become active. If tube 43 this condition and render tube 44 inactive and tube 43 active.

Throughout the circuits to be described a large number of these counting pairs are'employed all of which operate in the same manner. It will be found that the upper tube of each pair is normally active; that is, it is in a conducting state and has a low potential on its anode. Conversely the lower tube of the pair is normally inactive; that is, it is in a non-conducting state and has a high potential on its anode.

It will be noted that the anode cf each tube is in a potentiometer circuit. For tube 43 this potentiometer circuit may be traced from a high positive battery 50 through resistance 5| and resistance 52 to ground. The anode of the tube is connected to the potentiometer point between resistances 5| and 52, which for purposes which will appear hereinafter is-connected to a circle having the numeral 3 therein. Also a. circuit constituting a. potentiometer may be traced from battery 50, resistance 5|, the anode cathode path within the tube, resistance 53 and resistance 54 to ground. The resistances of the tube, 53 and 54 are thus in parallel with resistance 52 and under certain circumstances the tube will operate without the resistance 52. Now when the tube is non-conducting or inactive there being little if any current flow in this potentiometer circuit,

the potential of the anode (and the screen gridy of the companion tube) is at a comparatively high positive value. Thus, the tube 44 is enabled by a comparatively high positive screen grid po-I tential. However, when a negative potential is applied to both suppressor grids, both tubes 43 and 44 become non-conducting and hence a comparatively high positive potential is applied to has been active before the negative pulse, then` the screen grid of each. Hence, when the negative potential is removed from the suppressor grids both tubes are in a condition to become active or conducting. The choice of which one pre'- vails rests with the condenser 49 as hereinbefore pointed out.

When tube 43 is in an active or conducting state the current flow in its anode cathode circuit affects the potentiometer point between resistances 5| and 52 so that the potential thereof is at a comparatively low positive value. Hence the screen grid of the companion tube is at a comparatively low positive value and this tube is held in a non-conducting or inactive state.

The potentiometer circuit for tube 43 has been described. Tube 44 has a similar potentiometer circuit consisting of resistances 55, 56, 51 and 54.

It should be noted that as a tube goes from a non-conducting to a. conducting state its potentiometer point suddenly drops from a comparatively high to a comparatively low positive value. Hence as tube 43 becomes active the potentiometer point between resistances 5| and 52 drops and condenser 51 translates this sudden drop in potential into a negative pulse to be applied to the suppressor grids of tubes45 and 45. 'I'he charge thus put on the condenser 51 is dissipated through resistance 58 to ground.

'I'hus the pair of tubes 43 and 44 provide a' In the detailed circuit-a a ten pulse counter is shown in full and other similar counters are indicated whereby a number of pulses may be counted on a decimal basis.

There are' ten tubes 39 to d8 inclusive, provided,

of which ve, namely lib, lil, '183, 65 and il are normally active.

Tube el being normally active holds the. potential of the potentiometer point between resist-x positive pulse applied to the control grid of tube it causes a drop in the potentialof the ',anode.

Hence a'postive pulse incoming to tube tu appears on the suppressor grid of tube it as a negative pulse. The pair of tubes di and d2 are similar to the counting tubes heretofore described ex cept that theincoming negative pulse is applied only to the suppressor grid of tube Si. Tube di a i., 5 ement of Fig '4 is therefore rendered inactive and hence under Y control of condenser et the condition of tubes di and d2 is reversed, di now becoming inactive and tube d2 `becoming active.

The rst of the ten incoming pulses thus reverses the condition of tubes ii and l2 and by raising the potential o the point between resistances @t and si renders the tube 39 active and responsive to the following impulses. A small condenser te connected to the potentiometer point between resistances t@ and iii retards the rise or. potential on the screen grid of tube 39 sufficiently to prevent the incoming puise from aecting the tubes and ddl. other words the incoming puise spent before the tube 39 is rendered suiicientiy active to pass impulses.

The second impr-.ice controiling tube t@ and due to the t@ now is inverted into a negative pulse essor grid of tubes il?, and 353 so that on of the tubes '33 and dfi is reversed, 'tube becoming active and tube becoming inactive.

The third affaire reverses condition the tube '5, rendering tube active and tube nactive at the same time aiects the next p tubes and rendering tube inactive and tube et active.

The fourth 'impulse new reverses the condition oi tubes ani fit, rendering tube G23 inactive and tube active.

The i` f lse reverses the condition of both pairs i3 a and :it and di?, rendering tubes and de act/e and tubes it and et inactive.

it the same time a negative impulse is appiiedV through condenser to the suppressor grid o tube il and through condenser to the suppressor grid of tube 432. Thus the fifth impulse reverses the condition of tubes Lili' and @3B rendering tube it inactive and tube i8 active. The negative impulse applied to the suppressor grid of tube l2 will reverse the condition of tubes di and di?, tube il being rendered active and tube #l2 being rendered inactive. Tubes 39 and dil are also reversed, tube 39 being rendered inactive, and tube dii being rendered active.

The sixth impulse will reverse the condition of tubes di and 52, rendering tube lli inactive and tube i2 active. Tube Se is now rendered active, and tube it inactive as before.

The seventh impulse reverses the condition Qi tubes 63 and At, rendering tube '43 inactive and The eighth impulse reverses the condition of the pair 43 and te and the pair t5 and d6, render-y ing tubesY d3 and d6 active and tubes dlt and d inactive. y

The ninth pulse reverses the condition of the pair 3 and d6, rendering tube 43 inactive and tube it active. It will now be found that all the tubes are the reverse of normal. that is, tubes B2, di, lit, t8 and 3e are now active and tubes el, e3, 5, el and til are inactive.

The'tenth pulse results in a change back to normal. Here, as in the iifth pulse, a negative pulse is transmitted to tube e2 so that the condition of the pair of tubes. di and i2 is reversed.

On this tenth pulse as tube 48 becomes inactive its anode changes from a comparatively low .positive potential 'to a comparatively high positive potential. Thissudden rise in potential appears on the outgoing conductor 'iV and thus constitutes a positive pulse to the next set of tubes. IfI a plurality of sets of tubes of this nature is used the rst will serve to register the units digit of a number, and the succeeding sets will serve to register the tens, hundreds, thousands, and so on digits for as many places as may be desired.

l The above-described action o. the tubes may be visualized by the help of the chart, Fig. 8. In this chart the tubes are numbered one to eight, inclusive, to correspond to the numbers in the circles connected to the potentiometer points for the various tubes. Where a solid black dot appears in the chart it represents a comparatively high positive potential on such potentiometer point. VIn some cases there will be an outlined dot and then a dotted line to a solid vdot to indicate that the result of the pulse was to render the tube with the outlined dot active (comparatively low positive anode potential) and the other inactive (comparatively high positive anode potential) Thus pulse number one results in the reversal of the condition of tubes l and 2 (tubes iii and 32, respectively).

The chart of Fig. 8 thus depicts the permutation code whereby ten various combinations of the conditions of tubes li to d3, inclusive, may be used to record the ten digits. Fig. 3 also depicts the out pulse transmitted on the tenth pulse (the zero pulse for the tens recorder) in the form of a graph.

Fig. 5, with the exception of the gate and counter in the lower left-hand corner represents the integrator i5 or" Fig. i. From each counter there u. is brought a bundle of eight leads from the potentiometer points of the eight counting tubes, the numerals Within the circles at the left-hand ends thereof indicating that these leads are connected to the potentiometer points correspondinglydesignated. By means of a decade control et which has ten positions numbered 1 to 0 inclusive connections according to the permutation code of Fig. 8 may be made through a network of four resistances @9, lb, li and l2 to the grid of triode T3. These resistances are so proportioned that when all four and only when all four are connected to potentiometer points each of which is at a high positive potential, the tube i3 will become active. Thus if the decade control t3 is set at a particular point and when the arrangement of the tubes in the counter reaches that corresponding point, tube i3 will become active. lts anode is connected to a point in the potentiometer positive and negative batteries and hence when .li tube 13 becomes active the potential of the point between resistances and 16 falls from a comparatively high to a comparatively low positive potential. Tube 11| has its grid connected to a potentiometer point between resistances 18 and 11 and since this grid now also goes from a comparatively high to a comparatively low positive potential tube 16 becomes inactive. Hence the resistances 98 and 91 rises to affect the screen anode of tube 1li rises to a comparatively high controlled from the hundreds counter, resistance 8i is controlled from the tens counter and resistance 82 is controlled from the units counter. Now when the four counters simultaneously reach the the code arrangements in accordance with the setting of their decade controls, tube it will become active and change the potentiometer point between resistances 85 and d from a comparatively high to a comparatively low positive potential.

Since the rearrangement within the counters is proceeding at a rapid rate (800 movements per second by way of example) this potential change on the anode of tube 18 is only in the form of a negative pulse and this pulse marks the endrof the time interval which the decade controls were set to measure.

The negative pulse thus generated by the rapid fall of potential on the anode of tube 18 is used for two 'purposes as outlined in the description of the schematic of Fig. 1 (one) to enable the start circuit for the oscilloscope and (two) to enable the recycle counter.

The oscilloscope and its start circuit are shown in the right-hand portion of Fig. 6, the oscilloscope being shown schematically and the start circuit being shown in detail. The start circuit comprises a pair of tubes similar to the pair 4| and 42 of the counter in Fig. 4. This pair operates exactly like the counting pair 43 and 4t except that the two suppressor grids are not connected together so that a single negative impulse will operate to render tube 85 inactive and tube 8B active, these tubes then remaining in this condition until a negative reset pulse is transmitted over the reset lead 31 connected to the control grid of tube Bt. Therefore. the rapid fall of po- 'tential on the anode of tube 18 is translated by the condenser 8B into the necessary negative pulse for changing the condition of the pair of tubes 85 land 8S, whereupon the potentiometer point of the anode circuit of tube 05 goes from a comparatively low to a comparatively high positive potential. This is communicated over lead t0 to start the sweep of-oscilloscope 90. The circuits ot this device are'not shown as they are well known.

The pulse from the anode of tube 18 also enables the start circuit for the recycle counter, consisting of the pair of tubes 9| and 92. 'l'.l'irough condenser @s the rapid fail of potential of the anode of tube 18 is translated into the necessary negative pulse to reverse the condition of tubes 9| and 92, rendering tube si inactive and tube 92 active.

As tube @i becomes inactive the potentiometer point between resistances @d and @E rises and by the same token the potentiometer point between accesos grid o1' tube 00 to render tube |00 active. Thereupon the gate is opened so that current.i'rom the precision oscillator 22 may be admitted to the counter |02.l Connection from the oscillator 22 to the circuit of the control grid of tube |00 may be made at lead |0| (Fig. 3) so that the key 2| v may control -this gate as well as that of Fig. 3.

The counter 02 will respond to the'train of positive impulses into which tubes |00 and |03 convert the output of oscillator 22.

The counter |02 may be exactly the same as the counters of Fig. 4 and the output lead |05 may come from the anode circuit o1' the last tube of an integrator suchV as tube 18. Therefore when such tube in response to the counter rea-ching a predetermined count drops itsanode pocentral condenser |04 translates' this into the necessary negative pulse for application tothe suppressor grid of tube 92 whereupon the condition of tubes 9| and I92 is reversed, the gate is closed and the counter 02 is stopped on the count reached. Therefore the output conductor |05 is nowheld at a comparatively low positive potential, and this change is used to operate the recycle circuit of Fig. 3 in the manner to be shortly described.

The count 02 is employed to count oi a necessary time interval beginning with the transmission of the start pulse for the starting of the sweepcircuit of the oscilloscope. If the operator of this device requires a considerable time to readjust the decade controls after viewing the incoming signal then the counter |02 may be adjusted to 'count oi a correspondingly long signal. If on the other hand the operator through experience hasbecomeexpert in handling the ap- I paratus this period may be shortened. The period may be Xed if so desired and the decade adjustable controls dispensed with, the resistances such as 59 to 1.2 and 19 to 82 being permanently associated with certain given potentiometer points. Again if the relative times from the beginning of the operation to the start of the sweep of the oscilloscope and that taken by the sweep are quite diierent, then the time counted by the counter |02 may be made very short; in fact may be reduced to zero since the recycling operations may proceed to start a new cycle of operations even while the oscilloscope is performing its part. 'Ihis would have the advantage .of having the appearance of the return'location signal recur at more frequent intervals. The counter |02, then may be fixed or it may be adjustable or in certain extreme cases it may be eliminated altogether. In this latter case the lead |05 may be taken from'the potentiometer point connected to the anode of tube 92 so that the recycle circuit may be started by a drop in potential on conductor |05. 'Again it will be noted that the counter |02 is arranged in a circuit whereby it will count any predetermined number and then be stopped on that number whereas the counters of Fig. 4 will, as shown, pass by the number to be counted and continue to count for an additional period as determined by the gate and recycle circuit of Fig. 3.

When the potential of conductor |05 falls the triode 06 in Fig. 3 becomes non-conducting. Therefore the potentiometer formed of resistences iili, iut and |09 is affected and the point between resistanoes |00 and |09 changes from a comparatively low to a comparatively high positive value. This rise in potential is communi- Called through diode M0 to charge condenser faeeaeea This in turn raises the potential on'the grid of tricde H2. Y through resistances IIS and llt in a time and at a rate controlled by the capacity oi condenser Iii and the value of the resistances H3 and Hd. Hence although the potential on conductor 105 may almost immediately rise again due to the reset signal and the potential of the ancdeiof the diode liu may almost immediately fall, the main'- tenance of the comparatively high positive poten- The condenser ii'l will discharge condenser iinto the necessary negative imactive. vThe consequent rise in potential of the paratus is now returned to normal and the poteny tial on conductor 05 rises again as herenbefore described. In order to allow the various circuits suicient time to definitely return to normal this reset pulse is prolonged by the action of condenser i i i as described and by the slow discharge or condenser H5. Also condenser whose main function is to lower the potential of the poten;- tiometer point between resistances iii and Ht to in turn lower the potential of the potentiometer point between resistances i2@ and 92H through diode its, plays some part in, prolonging the reset pulse. Upon the enabling of tube H2 therefore the reset pulse is transmitted and the grid of tube 22 is lowered. Due tov condenser 423 the period during which the tube 22 is rendered nonconducting is prolonged for a considerable period depicted in Fig. 2 as the period during which the gate is cicsed. As tube 622 becomes non-conducting its anode circuit rises in potential and this rise being communicated to the grid of tube idd in the gate circuit controls tube mi through its screen grid to stop the now of negative pulses to the counters. is this action takes place the reset puise is transmitted so that as the counters and other apparatus are returned to normal the train or pulses to be counted are stopped. The triade due to condenser 23 maintains the high potential on the grid of tube 22@ for a period longer than the reset puise so that for a given pericci after the end or the reset pulse, tube H213 will be rendered non-conducting to start the entire train oi operations described.

ii manuaiiy operated reset key 25 may be provided to piace a negative potential on reset conductor It has heretofore been set forth that there are severai ways or slipping the time intervals between the duration or the time of the location signal and the comparison time being counted and two ways have been described. in accordance with the nrst way the start signal to the circuit ii oi Fig. 1 is delayed until nve hundred (or any other chosen number) is counted. In accordance with the permutation code depicted Fig. 8 the tube corresponding to tube la in the hundreds counter will go from an inactive to an active condition on the five hundredth impulse so that a conductor leading from the potentiometer point marked by the numeral $3 may be used to start the sonic transmitter and receiver circuit i2. If this point is therefore connected to conductor i2@ the ive hundredth impulse will then be translated by anode of tube A28 will then be communicated over conductor ltd leading to the sonic transmitter and receiver circuit |38 whereby a location signal is transmitted to locate a submarine designated in Fig. 6 by the numeral |32. The echo or return lsignal is then received and transmitted to the oscilloscope where it may be recognized by a trained operator. The circuits and interval arrangement of device iti are not here described asthey are well lrnown.y

In accordance with a second method of slipping the two time lintervals the start signal to the conductor ist is sent immediately. In this case as indicated inFig. '7 another-pair of tubes 53S its and i3d may be connected to the number 2.

potentiometer point of the units counterl so that in response to the rst impulse as the tube corresponding to the tube #l2 becomes active it will change the condition of tubes 33 and i3d, rendering tube 933 inactive and tube i3d active. .As tube i3d lbecomes active its anode drops from a compartively high to, a comparatively low positive potential and since this point may be connected to conductor i2@ the condenser i2? will translate this change into the necessary negative pulse to reverse the condition of tubes i29 and i2@ for the purposes hereinbefore set forth. The tubes H33 and i3d are used here since the potentiometer point 2 of the units counter: changes, continuously during a counting operation and it is only desired to have a single neg Therefore in the hundreds counter a circuit shown in fragmentary form within the rectanglel is employed. This consists of a hey which in its normal position as shown connects the reset conductor 3l to the lower tube lit. When the key i3@ is operated however the reset conductor is connected to the upper tube @i so that when the apparatus is returned to normal by the reset pulse the hundreds counter will be in the condition it would under other circumstances reach on the ve hundredth pulse. ln other words the counters are preset at ve hundred so that if the decade controls are set at 1,862 then only 1,362 pulses will be counted.

What is claimed is:

A time measuring device comprising a source of accurately timed pulses, an electronic pulse counter for counting pulses from said source, said pulse counter comprising a plurality of countersY in cascade each arranged to operate through a cycle of ten different counting conditions, means to set said pulse counter by adjusting said cascaded counters each to count a number corresponding to the corresponding integer oi a number on the decimal basis, means to A Y l 16 transmit a, signal at the .start of the said count, Numbery c Namel Date4 and means controlled by said 'counter to trans- 2,158,285 Koch May 16, 1939 mit a signal at the completion of said count. 2,143,035 Smith Jan. 10. 1939 OHMER. R. MILLER. 2,305,625 Lauer Dec. 22,1942 5 2,306,386 Hollywood Dec. 29, 1942 REFERENGES CETED I FOREIGN PATENTS The following references are of record in the Y Number Country Date me of this patent 355,705 Great Britain. Aug. 24, 1931 UNITED STATES PATENTS l 10 v OTHER REFERENCES Number Name Date Y R. s. I. March, 1938, pp. 83-89, article vby 932539 Hlden "om 31 1933 Lifschutz and Lawson. (copy in Div. 23.)

2,050,059 Koch Aug. 4,Y v1936 

